diff --git a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/RemoveUnusedOneToOneEquiJoinRule.java b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/RemoveUnusedOneToOneEquiJoinRule.java
index 9fe5e46..432ef10 100644
--- a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/RemoveUnusedOneToOneEquiJoinRule.java
+++ b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/RemoveUnusedOneToOneEquiJoinRule.java
@@ -23,6 +23,7 @@
 import org.apache.commons.lang3.mutable.Mutable;
 
 import edu.uci.ics.asterix.metadata.declared.AqlDataSource;
+import edu.uci.ics.asterix.metadata.entities.InternalDatasetDetails;
 import edu.uci.ics.asterix.metadata.utils.DatasetUtils;
 import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
 import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
@@ -45,14 +46,13 @@
  * Removes join operators for which all of the following conditions are true:
  * 1. The live variables of one input branch of the join are not used in the upstream plan
  * 2. The join is an inner equi join
- * 3. The join condition only uses variables that correspond to primary keys of the same dataset    
+ * 3. The join condition only uses variables that correspond to primary keys of the same dataset
  * Notice that the last condition implies a 1:1 join, i.e., the join does not change the result cardinality.
- * 
- * Joins that satisfy the above conditions may be introduced by other rules 
+ * Joins that satisfy the above conditions may be introduced by other rules
  * which use surrogate optimizations. Such an optimization aims to reduce data copies and communication costs by
  * using the primary keys as surrogates for the desired data items. Typically,
  * such a surrogate-based plan introduces a top-level join to finally resolve
- * the surrogates to the desired data items. 
+ * the surrogates to the desired data items.
  * In case the upstream plan does not require the original data items at all, such a top-level join is unnecessary.
  * The purpose of this rule is to remove such unnecessary joins.
  */
@@ -190,10 +190,12 @@
     private void fillPKVars(DataSourceScanOperator dataScan, List<LogicalVariable> pkVars) {
         pkVars.clear();
         AqlDataSource aqlDataSource = (AqlDataSource) dataScan.getDataSource();
-        int numPKs = DatasetUtils.getPartitioningKeys(aqlDataSource.getDataset()).size();
         pkVars.clear();
-        for (int i = 0; i < numPKs; i++) {
-            pkVars.add(dataScan.getVariables().get(i));
+        if (aqlDataSource.getDataset().getDatasetDetails() instanceof InternalDatasetDetails) {
+            int numPKs = DatasetUtils.getPartitioningKeys(aqlDataSource.getDataset()).size();
+            for (int i = 0; i < numPKs; i++) {
+                pkVars.add(dataScan.getVariables().get(i));
+            }
         }
     }
 
diff --git a/asterix-app/src/main/java/edu/uci/ics/asterix/file/DatasetOperations.java b/asterix-app/src/main/java/edu/uci/ics/asterix/file/DatasetOperations.java
index ccc5e85..565d916 100644
--- a/asterix-app/src/main/java/edu/uci/ics/asterix/file/DatasetOperations.java
+++ b/asterix-app/src/main/java/edu/uci/ics/asterix/file/DatasetOperations.java
@@ -301,7 +301,7 @@
             spec.connect(new OneToOneConnectorDescriptor(spec), scanner, 0, asterixOp, 0);
 
             IConnectorDescriptor sortMergeConn = new MToNPartitioningMergingConnectorDescriptor(spec,
-                    new FieldHashPartitionComputerFactory(keys, hashFactories), keys, comparatorFactories);
+                    new FieldHashPartitionComputerFactory(keys, hashFactories), keys, comparatorFactories, null);
             spec.connect(sortMergeConn, asterixOp, 0, btreeBulkLoad, 0);
         }
         spec.addRoot(btreeBulkLoad);